Enforce Agent Card constraints and sign the audit log with Ed25519 by sunilp · Pull Request #145 · jamjet-labs/jamjet

sunilp · 2026-10-11T01:43:03Z

Agent Card constraints were declared and documented as enforced, but nothing checked them. Now they are enforced at the shared guard (node_guard::guard_item), so the in-process worker, POST /work-items/claim and the completion gate all make the same decision.

allowed_tools, blocked_tools, require_approval_for and allowed_delegations are enforced. A node acts for the workflow's agent_ref or for its own acts_for, and has to be allowed by every agent it acts for. Matching uses the tool name, and for ADK dispatch it also uses the resolved handler. An unregistered agent fails closed.
The Python SDK can attribute workflows and nodes to an agent.
The audit log can be signed with Ed25519 (JAMJET_AUDIT_SIGNING_MODE=ed25519, with the key in JAMJET_AUDIT_ED25519_KEY or JAMJET_AUDIT_ED25519_KEY_FILE). The public key is published in did.json as #audit-key, so a third party can verify the log offline. Verifiers use strict Ed25519 and strict entries.
The docs now claim only what the code does.

Test-first, mutation-checked, independently reviewed. The review's findings are fixed in 4428ac8, 95945d6 and 5a75502.

🤖 Generated with Claude Code

Summary by CodeRabbit

New Features
- Workflows and agents can now reference registered Agent Cards, whose tool, approval, and delegation rules are enforced at runtime.
- Runtime audit logs can optionally use Ed25519 signatures, with public verification keys published for offline verification. HMAC remains the default.
- Added Python support for verifying signed audit exports, including chain integrity and signature validation.
Bug Fixes
- Duplicate agent registrations are now rejected, and unreadable agent registries fail closed during enforcement.

coderabbitai · 2026-10-11T01:43:13Z

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Reviewing files that changed from the base of the PR and between 1586997 and 265f556.

📒 Files selected for processing (2)

sdk/python/jamjet/runtime_audit.py
sdk/python/tests/test_runtime_audit.py

📝 Walkthrough

Walkthrough

This change adds Agent Card references and runtime enforcement for tool, approval, and delegation constraints. It also adds optional Ed25519 audit signing, publication of its public key, and Python tools for offline audit verification. HMAC remains available as the default signing mode.

Changes

Agent Card enforcement

Layer / File(s)	Summary
Agent attribution in workflow IR `sdk/python/jamjet/agents/agent.py`, `sdk/python/jamjet/compiler/agent_ir.py`, `sdk/python/jamjet/workflow/`, `runtime/ir/src/workflow.rs`, `runtime/ir/src/validate.rs`, `sdk/python/tests/agent_ref*`, `sdk/python/tests/fixtures/agent_ref_agent_ir.json`	Python APIs and compilers validate and serialize workflow-level and node-level `agent_ref` values. Rust IR accepts the optional fields. Tests cover validation, generated IR, and content versioning.
Card constraint evaluation `runtime/policy/src/`, `runtime/policy/tests/function_node_names.rs`, `runtime/agents/src/`, `runtime/workers/src/*`	Policy helpers match tool names and resolved handlers. Worker guards check agent-card constraints and combine card approval gates with policy decisions. The worker pool can pass an agent registry to workers.
API gates and enforcement coverage `runtime/api/src/*`, `runtime/api/tests/agent_allowed_tools.rs`, `CHANGELOG.md`	Claim and completion gates pass agent references, remote-agent mappings, and the registry to worker guards. Integration tests cover tool restrictions, approvals, delegation, and fail-closed cases across transports and backends.

Ed25519 audit signing and verification

Layer / File(s)	Summary
Signing and verification primitives `runtime/audit/Cargo.toml`, `runtime/audit/src/*`, `runtime/audit/tests/ed25519_signing.rs`	The audit signer supports HMAC and Ed25519 modes, including key loading and public-key verification. The crate adds single-entry verification. Tests cover keys, signatures, environment configuration, and HMAC behavior.
Audit key publication `runtime/api/src/routes.rs`, `runtime/api/tests/audit_ed25519.rs`, `runtime/api/Cargo.toml`, `CHANGELOG.md`	The API conditionally publishes an Ed25519 public JWK in its DID document. Integration tests verify served audit entries with that key and check that HMAC mode does not publish verification methods.
Python offline audit verification `sdk/python/jamjet/runtime_audit.py`, `sdk/python/tests/test_runtime_audit.py`, `sdk/python/tests/fixtures/runtime_audit_ed25519.json`, `sdk/python/CHANGELOG.md`	The Python SDK validates audit entries, hashes, signatures, and chain links. It also orders entries and extracts the audit public key from a DID document.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~60 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant PythonCompiler
  participant WorkflowIR
  participant Worker
  participant NodeGuard
  participant AgentRegistry
  participant PolicyChecks
  PythonCompiler->>WorkflowIR: serialize agent_ref values
  Worker->>NodeGuard: check node with AgentScope
  NodeGuard->>AgentRegistry: look up attributed agent cards
  NodeGuard->>PolicyChecks: evaluate card and policy constraints

sequenceDiagram
  participant AuditSigner
  participant AuditEnricher
  participant ServeDidDocument
  AuditEnricher->>AuditSigner: sign audit entry
  ServeDidDocument->>AuditEnricher: access configured signer
  AuditEnricher-->>ServeDidDocument: return signer
  ServeDidDocument->>AuditSigner: get public JWK

Merge Risk: 🔵 Low · up to 15869

Agent Card enforcement and Ed25519 audit signing appear sound. One small follow-up remains: the Python audit verifier can raise unexpected exception types on some malformed exports instead of its documented ChainError. Tampered entries are still not accepted.

Pre-merge checks | 4 | 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 255 functions across 29 files. (6 skipped…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely summarizes the two main changes: enforcing Agent Card constraints and adding Ed25519 audit-log signing.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 255 functions across 29 files. (6 skipped: 6 unsupported.)

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The Agent Card declared allowed_tools and nothing read it, while the security guide said the runtime enforced it. A workflow or node now names the agent it acts for with agent_ref, and guard_item, which the claim route, the in-process worker and the completion gate all run, refuses a node whose tool is not on that agent's list before any policy or approval is considered. The policy chain still applies on top. An ADK dispatch call must be allowed by its name and by the code its tools entry resolves to, so an allowed name cannot run other code. A function node is matched on its handler, never its node id, and a dispatch-marked node that is not the ADK dispatcher is matched on its own handler too. Absent or empty lists restrict nothing, since cards cannot tell unset from empty and stored cards carry []. Unregistered agents and a missing registry refuse the node; an unreadable registry holds it. Finalizer nodes are named by their tool_ref so lists and policy see them, the in-memory registry refuses a duplicate URI as SQLite already did, and AutonomyConstraints fields are optional on input.

HMAC signing uses one shared key, so anyone who can check the audit log can also forge it. JAMJET_AUDIT_SIGNING_MODE=ed25519 signs every entry with a seed only the runtime holds, and publishes the public key in /.well-known/did.json as #audit-key. Each entry is signed rather than a chain head at intervals: the chain spans every tenant, so a tenant's slice is not contiguous and only a per-entry signature can be checked from it. The signature covers a JCS statement naming the entry hash, the key id and a spec tag, matching AgentBoundary's canonical encoding; the entry hash keeps its existing construction so chains already written still verify. HMAC stays the default and is byte-for-byte unchanged. A bad Ed25519 key leaves entries unsigned instead of falling back to HMAC, and the key is kept out of logs, errors, Debug and responses. The Python SDK gains jamjet.runtime_audit to verify a GET /audit export offline, tested against a vector the Rust tests write.

agent_tool nodes had no tool name, so an agent restricted to search_* could still call any remote agent through one. They are now named by their explicit target, for policy too, and nodes that pick their target at run time (coordinator, agent discovery, an auto agent tool) are refused under a list since there is nothing to check. A bare name pattern matched across a handler's module path, so read_* allowed read_utils:delete_everything. Bare names now match only the function's own name; patterns with a path still match the reference. The docs now state the limits the review raised: the handler check needs a tools map entry, agent status is not consulted, cards are global and first registration wins.

The Python verifier accepted a small-order public key, under which any signature verifies, and a small-order R, both of which the runtime's verify_strict refuses; OpenSSL checks neither. It now refuses both, and refuses entries whose fields Rust would not read, so a verified entry is one the runtime could have written. A test now separates verify_strict from plain verify (a small-order R made with the private key), which no test caught before. The runtime warns when the key file is readable by other users, and the docs say to prefer the file over the environment, that old keys are needed after a rotation, and when to verify without links.

Both were declared on the card and read by nothing. They now apply at the same first step as allowed_tools and match the same identities, so a call is caught by its name or by the code it resolves to. A card block refuses the node even when the tool is on the card's own allow list. A card gate turns the chain's allow into the ordinary approval request, so it binds the same action digest and takes the chain's deadline, and a dispatch is approved as a whole batch like a node-level gate. Both stay additional to tenant, workflow and node policy.

The field was declared and read by nothing. The concrete delegation points are agent nodes, agent_tool nodes with an explicit target and a2a_task nodes; each names its target in the IR, so the shared guard checks that name against the card's list before the node runs. Coordinators, agent discovery and auto agent tools pick their target at run time, so there is nothing to check and they are refused under a list. An empty list restricts nothing, as with allowed_tools. Subgraphs run a child workflow rather than an agent and are left out.

Without a way to set agent_ref, an SDK user had to hand-edit IR JSON to get any agent card enforced. Agent(agent_ref=...) now emits it on the durable path, and YAML takes agent_ref in the workflow header, the agent-first agent block and fleet units, and acts_for on a node, since a node's agent_ref already names the agent an agent node calls. The value is part of the agent graph's content version, so a graph compiled for one agent is never reused for another. A Rust test runs the IR the Python compiler writes and shows the card enforced through it.

Several pages said the runtime enforces autonomy levels and budgets and routes escalations to a supervisor or a human. It checks token and cost budgets only for a bounded_autonomous card on an agent node, in the in-process worker; iteration and tool-call limits compare against counters nothing increments; time_budget_secs is never read; and no escalation is routed anywhere. The agent guide now carries one table of what each constraint does and where, and the other pages that described constraints point to it instead of restating them.

Clippy flagged it after the harness was split into run_in and fire.

A card gate on a dispatch call took over the node-level approval path, so the request named only the card-gated tool, showed no calls when the payload was too large to preview, and its approval waved through calls the policy chain gated. A chain-blocked call in the same batch was turned into a request instead of a refusal. Card-gated calls now join the dispatch guard's own per-call request, which lists every gated call with its arguments and binds them, and chain blocks are evaluated first. An a2a_task is checked against allowed_delegations by the URL its name maps to, since the author writes both. The autonomy check refuses when the registry cannot be read instead of running the node. YAML refuses agent_ref on a non-agent node, which used to be dropped silently. The docs drop the claims the review showed were still not exactly true.

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Inline comments:
Review comments at @sdk/python/jamjet/runtime_audit.py:
- Around line 292-295: Update verify_entries to validate signature and
entry_hash as strings, and prev_hash as either None or a string, before using
them. Include OverflowError and AttributeError in the exceptions converted to
ChainError("malformed") around entry_content_hash so malformed entries preserve
the verifier’s ChainError contract.

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📥 Commits

Reviewing files that changed from the base of the PR and between f77dbe2 and 1586997.

⛔ Files ignored due to path filters (7)

docs/architecture/agent-model.md is excluded by !docs/**
docs/guides/agent-model-guide.md is excluded by !docs/**
docs/guides/concepts.md is excluded by !docs/**
docs/guides/hitl.md is excluded by !docs/**
docs/guides/security.md is excluded by !docs/**
docs/guides/yaml-reference.md is excluded by !docs/**
docs/rfcs/RFC-005-agent-model.md is excluded by !docs/**

📒 Files selected for processing (35)

CHANGELOG.md
runtime/agents/src/card.rs
runtime/agents/src/memory_registry.rs
runtime/api/Cargo.toml
runtime/api/src/main.rs
runtime/api/src/routes.rs
runtime/api/tests/agent_allowed_tools.rs
runtime/api/tests/audit_ed25519.rs
runtime/audit/Cargo.toml
runtime/audit/src/chain.rs
runtime/audit/src/enricher.rs
runtime/audit/src/lib.rs
runtime/audit/src/signer.rs
runtime/audit/tests/ed25519_signing.rs
runtime/ir/src/validate.rs
runtime/ir/src/workflow.rs
runtime/policy/src/allowed_tools.rs
runtime/policy/src/dispatch.rs
runtime/policy/src/engine.rs
runtime/policy/src/lib.rs
runtime/policy/tests/function_node_names.rs
runtime/workers/src/dispatch_guard.rs
runtime/workers/src/node_guard.rs
runtime/workers/src/pool.rs
runtime/workers/src/worker.rs
sdk/python/CHANGELOG.md
sdk/python/jamjet/agents/agent.py
sdk/python/jamjet/compiler/agent_ir.py
sdk/python/jamjet/runtime_audit.py
sdk/python/jamjet/workflow/bundle.py
sdk/python/jamjet/workflow/ir_compiler.py
sdk/python/tests/fixtures/agent_ref_agent_ir.json
sdk/python/tests/fixtures/runtime_audit_ed25519.json
sdk/python/tests/test_agent_ref.py
sdk/python/tests/test_runtime_audit.py

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An out-of-range sequence, or a hash, signature or prev_hash that is not a string, raised OverflowError or AttributeError. The export is untrusted input, and a caller that catches ChainError would crash on it. Found by CodeRabbit on #145.

sunilp force-pushed the allowed-tools-and-signing branch from 5a75502 to 1fe6f6a Compare October 11, 2026 02:04

sunilp force-pushed the approval-deadlines branch from a43c224 to bc59ab3 Compare October 11, 2026 02:04

sunilp force-pushed the allowed-tools-and-signing branch from 1fe6f6a to acc528f Compare October 11, 2026 02:05

sunilp force-pushed the approval-deadlines branch from bc59ab3 to 93fb3dc Compare October 11, 2026 02:05

Base automatically changed from approval-deadlines to main October 11, 2026 02:09

sunilp added 10 commits October 11, 2026 07:39

Drop a needless borrow in the agent card test harness

4de9323

Clippy flagged it after the harness was split into run_in and fire.

sunilp force-pushed the allowed-tools-and-signing branch from acc528f to 1586997 Compare October 11, 2026 02:09

sunilp marked this pull request as ready for review October 11, 2026 02:09

coderabbitai Bot reviewed Oct 11, 2026

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Comment thread sdk/python/jamjet/runtime_audit.py Resolved

sunilp merged commit 5314533 into main Oct 11, 2026
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sunilp deleted the allowed-tools-and-signing branch October 11, 2026 03:02

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Enforce Agent Card constraints and sign the audit log with Ed25519 - #145

Enforce Agent Card constraints and sign the audit log with Ed25519#145
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